Sukhoi Su-15/ 21 ‘Flagon’

The Su-21 Flagon will always be remembered for the tragic shooting down of a Korean Airlines Boeing 747 on 1st September 1983.  Flight 007 was mistakenly believed to be spying for the US and after it failed to respond to radio hails and a burst of cannon fire across its bows so to speak, Su-21 no 805 pulled behind and fired one missile into the airliner with tragic results, a sad event in the history of the Cold war.

The Su-15 provided the bulk of Soviet air defence for many years; its development came about due to the threat from US strategic bombers in particular the possibility of a mach 3 bomber being developed (such as the XB-70). In response the Soviets rapidly upgraded their all weather interceptor capability and designs such as the MiG-25 Foxbat and MiG-23 Flogger were developed. MIG’s design rival Sukhoi already had an all weather interceptor, which entered service as the Su-9, which was improved in 1966 as the Su-11.  When in 1962 the requirement was set out for an interceptor to counter any mach 3 bombers the US may develop (they never did) Sukhoi went about designing an interceptor with much better, faster performance than anything that had gone before, but instead of trying anything radical Sukhoi took the path of least resistance and adapted existing technology, making it bigger and better.

Making such a fast, heavy delta plane would require long runways but that was never considered a problem for the Soviets. The landing speed was going to be as high as 186mph (300km/h), which would require a long distance to stop especially with a heavy titanium reinforced airframe.  In 1963 the designation Su-15 was assigned and 20 developmental aircraft were produced with one painted black being flown on the 1967 Aviation Day by the Soviet test pilot V Ilyushin son of the famous aircraft designer.  In June 1967 one of the first groups to enter service was an aerobatic team painted a golden red colour known as the ‘Golden Hawks’.

The new fighter was a large aircraft with very obvious large nose radar believed to be the same type as fitted to the MiG-25, despite the aircraft carrying much shorter range missiles. The aircraft also had distinctive box shaped air intakes behind the cockpit body.  Engines were almost certainly the very powerful AL-21F rather than a lower powered engine as first thought in the West.  Many parts were similar to the Su-11 including the weapons namely 2 AA-3 ‘Anab’ AAM carried on under wing pylons.  One puzzle was a large pod on top of the vertical tail plane, which was believed to be a rear facing radar, but it never became standard.

Small numbers of Su-15s entered Soviet service in 1968 and were code named ‘Flagon-A’ by NATO. An experimental short take off and landing version was code named Flagon-B although the Su-15VD as the Russians classified it, never saw production. The Su-21 is believed to have been the main production version with about 500 serving on the front line during its heyday and a further 900 in reserve and training units. The Flagon was gradually replaced by MiG-29, MiG-31 and Su-27s in service during the 1980s.

Max Speed;  2655 km/h (1,650 mph)
Service Ceiling; 65,615 ft (20,000m)
Combat Radius;  725 km (450 miles)
Climb rate;    2 minutes 30 seconds to reach 36,000ft (13700m) 

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How to cite this article: Dugdale-Pointon, T., (29 March 2007), Su-15/ 21 ‘Flagon’,

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